Wind Tunnel Aerodynamics

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Wind Tunnel Aerodynamics

• By
• Dr. Charles Trefny
• 20 Sept 2002

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Aerodynamics The field of science and
engineering dealing with the effects of air
moving around solid objects.
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Aerodynamicists Predict what will happen in a
given situation using physical laws, math,
wind-tunnels and computers
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Air has mass and obeys Newtons laws. 100
gallons of air has a mass of about 1 pound. We
must speed-up, slow-down, or change the direction
of the air to generate a force. Look for this in
the following examples of aerodynamics
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Wind tunnels are used to predict the amount of
force generated by solid objects. This helps
aerodynamicists choose the proper size for things
such as wings, spoilers, and parachutes. Informat
ion obtained in wind tunnels is used to improve
the design of anything affected by
wind. Wind-Tunnels come in all shapes and sizes
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Open-Return Type Wind-Tunnel
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Closed-Return Type Wind-Tunnel
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Blow-Down Type Tunnel
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Wind Tunnel Test Examples
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Similarity Principle Allows us to test a small
model and get information about the full-size
object Well use a parachute for example
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Will the egg break?
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Similarity Principle For similar shapes, this
ratio always comes out to the same number.
Weight
Density x Speed x Speed x Diameter x
Diameter
Dont worry, its just a FRACTION!!!
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Do a wind tunnel test to find out what C is for
the parachute
Weight
C
Density x Speed2 x Diameter2
All known in the wind tunnel!
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Computers can also be used to solve problems in
aerodynamics. The computer solves complex
mathematical equations that are based on Newtons
laws of motion The wing or airfoil is a
classic problem